int get_choice(void) { const char choiceList[] = "abcdq"; int ch; printf("\n"); printf("A.add \tB.subtract\n"); printf("C.multiply\tD.divide\n"); printf("Q.quit\n"); printf("Please the operation of your choice:"); do { ch = tolower(_getch()); } while (!strchr(choiceList, ch)); _putch(ch); return ch; }